27. Rezolvați sistemele:
a)
c)
(2x - y² + 5 + x - 2x -
x-2y-7-1
3
x-3y-5+5
2
x+2y+2,
3
+
x+y-9 x+4y-7
4
x-y+5
5
1-6
3
3x-2y+3
b)
d)
x-2y-15 3x+y-10
5
2
x+3y-2 2x+y+7
4
3
2x-3y+6_x-4y-2-3
-2
=-2
4
6
x+3y-4 2x-3y-7
+
3
5
=1